Re-analysis of data on a0(1450) and a0(980)

TL;DR

This paper re-analyzes data on the scalar mesons a0(1450) and a0(980), refining their parameters and clarifying their decay properties using comprehensive dispersive corrections and multiple datasets.

Contribution

It provides updated, more stable parameters for a0(1450) and a0(980), resolving previous ambiguities and clarifying decay ratios with full dispersive corrections.

Findings

Mass of a0(1450) peak is 1448 MeV with width 192 MeV.

Parameters of a0(980) are precisely updated.

No evidence found for a0 near 1300 MeV.

Abstract

Four sets of data determining parameters of a0(1450) and a0(980) are re-analysed. These are Crystal Barrel data for pbar-p annihilation at rest to eta-pizero-pizero in (i) liquid hydrogen and (ii) gas, and to (iii) K0_L-picharged-Kcharged and (iv) omega piplus-piminus-pizero (mostly omega-rho-pi). Dispersive corrections due to opening of inelastic thresholds are treated fully. This stabilises parameters of a0(1450) substantially. The mass of its peak is 1448 +-13(stat) +- 25(syst) MeV and its mean full width at half maximum is 192 +-9 +-9 MeV. The pole position is 1432 +- 13 +- 25 - i(98 +-5 +-5) MeV. At the peak, eta-pi, omega-rho and a0(980)-sigma decay intensities are in the ratios 1 : 9.2 +- 0.8 +- 1.3 : 3.1 +- 0.2 +- 0.9. There is no evidence for a separate a0 near 1300 MeV claimed by Obelix. Parameters of a0(980) are updated to M = 987.4 +- 1.0 +- 3.0 MeV, g^2(eta-pi) = 0.164 +- 0.007 +- 0.010 GeV^2, g^2(KK)/g^2(eta-pi) = 1.05 +- 0.07 +- 0.05. The nature of the prominent J^{PC} = 0^{-+} signal in omega-rho is also clarified.